@capjamesg's #5 tried to enable mf2py's new img alt output flag, but it's evidently not working. eg the h-entry u-photo in https://snarfed.org/2022-12-06_48532 has an alt, but https://python.microformats.io/?url=https://snarfed.org/2022-12-06_48532 isn't showing it.